Uses for labels, stickers, and other adherable substrates can be found in almost every aspect of life—school projects, professional presentations, file labels, CDs and tapes, computer disks, containers for food in the freezer, etc. Traditionally, such adherable substrates used permanent pressure-sensitive adhesives which made the labels difficult to remove without the assistance of a solvent. This situation can oftentimes be problematic because the label can tear, leaving label remnants behind on the surface to which it was adhered and rendering the label useless.
For example, consider a person putting together a professional presentation. Many such presentations involve positioning items such as charts and photographs onto a large posterboard. One device which can be used to perform this task is shown in U.S. Pat. No. 4,331,727. The device of the '727 patent is a roll of release-coated substrate coated on one side with pressure-sensitive permanent adhesive. The user unrolls the substrate, then takes an item, such as the photograph or chart, and presses it against the unrolled substrate to transfer the adhesive to the item. The item can now be adhesively bonded to the posterboard.
The problem with this type of device is that the adhered item cannot be easily removed from the posterboard and repositioned without damaging the board and the adhered item. Thus, hours of hard work could be wasted simply by permanently adhering the wrong chart to the wrong board or in the wrong place on the right board. It can be appreciated that similar problems arise in the fields of arts and crafts, school projects, and other areas.
Another example of this type of problem is found in adherable window signs. Many stores and restaurants use signs advertising sales, new items, holiday themes, etc. which are adherably bonded to the inner surface of a window with a permanent pressure sensitive adhesive. When the proprietor desires to remove the sign, he or she must typically use a solvent and a scraper to remove the sign. Misuse of the scraper can damage the window and almost always destroys the sign itself.
Removable or repositionable adhesives can obviate the problems associated with the permanent nature of permanent adhesives. Conventionally, in order to create a substrate which adheres to a contact surface in a removable or repositionable manner, the substrate is coated with a primer and then the primed area is coated with a commercially available liquid repositionable adhesive or a relatively solid “glue-stick” of such adhesive. This process can become somewhat messy due to the potential for spilling either the liquid adhesive or the primer. Also, the adhesives sometimes are available in a spray form which can be difficult to apply evenly over a substrate surface. Certain spots on the substrate can also be overlooked or missed during manual application of the primer and adhesive. Furthermore, it is undesirable to purchase a bottle of primer and a bottle of liquid repositionable adhesive or a glue-stick if these materials are only to be used for a limited number of applications.
U.S. Pat. No. 5,558,913 discloses a primerless adhesive construction comprising a backing, a layer of permanent adhesive, a layer of removable adhesive, and a release liner. The permanent adhesive layer bonds the removable layer to the backing, thereby allowing the backing to be removably adhered to a contact surface. The ratio of removable adhesive to permanent adhesive is greater than 1:1 and the density of both adhesive layers combined is in the range of 18–25 grams per square meter. The subject matter of the '913 patent, however, does not address the problems discussed above.
The '913 patent discloses the permanent layer as being bonded to the backing and is mainly concerned with pre-made labels and stickers of predetermined size, such as mailing labels and file folder labels. The subject matter disclosed in the '913 patent, however, cannot be used to make pre-existing non-adherable substrates, such as photographs, charts, and window signs, into repositionably adherable substrates.
Consequently, there exists a need for an adhesive transfer device which can be used to create repositionably adherable substrates of different types and sizes for a wide variety of applications.
It is therefore an objective of the present invention to meet the above-described need. In order to achieve this objective, the present invention provides an adhesive transfer device for selectively making a repositionably adherable substrate from a selected substrate. The device comprises a base substrate and a layer of pressure-sensitive repositionable adhesive disposed on a portion of the base substrate. A layer of pressure-sensitive permanent adhesive is disposed adjacent to the repositionable adhesive layer opposite the base substrate portion.
A release surface removably engages the permanent adhesive layer opposite the repositionable adhesive layer and the base substrate portion. The nature of the release surface is such that the base substrate and the structure providing the release surface can be moved apart from one another so as to separate the release surface from the permanent adhesive layer and leave the adhesive layers on the base substrate with the permanent adhesive layer exposed, thereby enabling the exposed permanent adhesive layer to be adhesively bonded to the selected substrate by engaging the selected substrate with permanent adhesive layer. The adhesive layers are provided such that the base substrate and the selected substrate can be moved apart from one another so as to separate the base substrate from the repositionable adhesive layer and leave both the adhesive layers on the selected substrate with the repositionable adhesive layer exposed, thereby allowing the selected substrate to be (a) repositionably adhered to a contact surface by engaging the exposed repositionable adhesive layer with the contact surface and applying pressure to the selected substrate and (b) thereafter be removed from the contact surface and repositionably adhesively bonded to another contact surface.
It is preferred that the nature and the thickness of the permanent adhesive layer be sufficient to bond to textured surfaces such as cloth, carpeting, and the like. When relatively low amounts of adhesives are used the permanent layer is capable of adhering to smooth surfaces such as glass and paper, but has difficulty in bonding to textured surfaces such as cloth. The adhesive layers disclosed in the '913 patent are sufficient only for bonding with a clean, smooth backing, such as the pre-fabricated backing provided during assembly of the label. In contrast, the preferred thickness and nature of the permanent layer according to the present invention allows the adhesive layers to bond to a wide variety of materials, including both clean, smooth surfaces and uneven, textured surfaces.
Preferably, the weight ratio of repositionable adhesive to permanent adhesive is greater than 1:1. This ratio is preferred to ensure that the permanent adhesive does not mix with and overcome the repositionable adhesive to thereby cause the latter to lose its repositionable characteristics. However, this ratio is not critical to the present invention.
The preferred type of adhesive for the repositionable adhesive is a microsphere adhesive. Microsphere adhesives exhibit superior bonding characteristics for a wide range of surfaces. In addition, microsphere adhesives provide excellent control over the bond strength and characteristics. The preferred type of adhesive for the permanent adhesive is an acrylic emulsion based adhesive.
The broad principles of the present invention may be practiced in a variety of ways. The present application discloses a variety of exemplary devices which utilize the principles of the present invention, including adhesive transfer sheets, an adhesive transfer cartridge to be used in conjunction with an adhesive transfer apparatus, and a substrate dispenser for dispensing a substrate coated with adhesive materials. The principles of the present invention, however, are not limited to these exemplary devices.
Other objects, features, and advantages of the present invention can be appreciated from the following detailed description, the accompanying drawings, and the appended claims.